1. Field of the Invention
The present invention relates to superparamagnetic particles consisting of superparamagnetic one-domain particles and aggregates of superparamagnetic one-domain particles of iron oxides, mixed iron oxides or iron to whose surfaces are bound inorganic substances which optionally may have further binding sites for coupling tissue-specific binding substances, diagnostic substances or pharmacologically active substances.
2. The Prior Art
Patent EP-B-0284549 describes superparamagnetic one-domain particles of iron oxide, mixed iron oxide or iron with a particle size ranging from 3 to 20 nanometres, to whose surfaces are chemically bound organic substances of the group of phosphate, diphosphate, polyphosphate, thiophosphate, phosphonate or thiophosphonate group-containing polyalkylene glycols, phosphate group-containing nucleotides, their oligomers or their polymers as well as phosphate group-containing carbohydrates, which may have further binding sites.
Patent DE-A-4309333 describes stable, degradable aggregates with a particle size ranging from between 10 and 1000 nanometres with defined behaviour in a magnetic field whereby the aggregates consist of several small superparamagnetic one-domain particles of iron oxide, mixed iron oxide or iron with a particle size ranging from 3 to 20 nanometres to whose surfaces are chemically bound substances of the group of phosphate, diphosphate, polyphosphate, thiophosphate, phosphonate or thiophosphonate group-containing polyalkylene glycols, carbohydrates or of the phosphate group-containing nucleotides, their oligomers or their polymers.